Performances of two different materials (water and phase change material) were studied as heat storage medium in passive design of buildings. An experimental and numerical simulation method was applied. The experimental study was conducted in the laboratory environment on double glazed window sample. Numerical simulation model was formulated to simulate the transient heat transfer through the window system. The results show that the PCM filled window can be protected from rapid overheating due to latent heat of the phase change material. Numerical model showed good matching with experiment; therefore, the model can be used for the window system performance evaluation as energy storage unit under different configurations. Received 19 May 2016, Revised 26 Oct 2016, Accepted 31 Oct 2016

In this article, temperature-responsive window system based on phase change materials is studied by using experimental and numerical methods. The problem is analyzed for the real case (natural environment) and lab environment. Impact of glazing cavity size on the temperature flattening period and its limitations are determined and mathematically described. The results show that the design is effective in reducing interior air temperature variation by increasing the cavity thickness up to 24 mm, which is limited by solid/liquid volume fraction for particular environment.

Thermal energy storage in a vertically oriented, phase-change material (PCM) filled coil heat exchanger is investigated through experiments and numerical calculations based on computational fluid dynamics (CFD). History of temperature at a number of monitoring points, heat transfer rate and change of solid/liquid phase fractions during the melting and solidification process are recorded. In the melting stage (charging) acceptable agreement of experimental results and numerical prediction is observed. During the solidification process (discharging), shrinkage of PCM triggered by cooling is seen, resulting in air gaps between the heat-transfer pipe and storage medium, which makes heat transfer limited.

This paper presents some of the results from numerical isothermal 3D computations as well as experimental measurements of the liquid film flow down an inclined solid wall. Computational fluid dynamics (CFD) simulation including a two-phase (water/air) volume-of-fluid model with freesurface, and visualization of the liquid film using a high-resolution camera are conducted. The film response for different entrance flow rates and different conditions at the film-side boundaries is examined. The flow properties and quantities of interests are liquid-film thickness, the shape of the liquid-film surface, and the surface-wave development. The simulation and experimental results are compared showing an acceptable agreement.

In order to increase energy efficiency of heating plants and obtain lower CO2 emission into atmosphere, there is a tendency to keep exhaust-gas temperature lower than its typical value referred to as “acid dew point”. As a result, vapor condensation of wet flue gas appears in chimneys. Condensation occurs when the surface temperature is below the dew point of the vapor-gas mixture. Therefore, Vapor-Liquid Equilibrium models are required in order to determine the dew point of the mixture. A numerical model of turbulent vapor-air mixture flow through a chimney is presented. The velocity, temperature, as well as species fields are calculated via a finite-volume CFD code, whose validation is conducted employing a real object in chimney. The experiment on heat and mass transfer of a two-phase, two-component system is done Comparisons of gas temperature and pressure at the wall are shown, revealing a good prediction obtained by the model presented.

Keywords:Wind energy; Simulation; Complex terrains; Computational Fluid Dynamics (CFD). ABSTRACT A method for simulation of wind flows, which is based on computational fluid dynamics (CFD) approach, is tested in a region with complex terrain. For the region adopted, limited measurements of wind velocity and direction exist, and are used as the input data for specification of boundary conditions. The resulting flow field quantities (wind power density and turbulent kinetic energy) are shown, indicating the parts of the region which are suitable or unsuitable for wind turbine positioning. The method employed offers a number of benefits for efficient and reliable estimation of wind resources.

A process for simulation of heat storage in phase-change materials (PCM) based on computational fluid dynamics (CFD) approach is presented. Cylindrical shape of PCM heated by an inner tube is analysed, in which two different heat-transfer mechanisms are considered: (i) conduction only, and (ii) combined natural convection and conduction. The physical properties of a PCM from literature are adopted for testing, and describe a typically used, commercial paraffin-based material. This preliminary study indicates successful use of CFD simulations in investigation and analysis of thermal energy storage in PCMs.